/*
* Truncate a file.
*
* Locking: gets/releases vnode lock.
*
* Requires up to 4 buffers.
*/
static
int
sfs_truncate(struct vnode *v, off_t len)
{
struct sfs_vnode *sv = v->vn_data;
int result;
lock_acquire(sv->sv_lock);
reserve_buffers(SFS_BLOCKSIZE);
result = sfs_itrunc(sv, len);
unreserve_buffers(SFS_BLOCKSIZE);
lock_release(sv->sv_lock);
return result;
}
// Drop a reference to an in-memory inode.
// If that was the last reference, the inode cache entry can
// be recycled.
// If that was the last reference and the inode has no links
// to it, free the inode (and its content) on disk.
void
sfs_iput(struct inode *ip)
{
struct sfs_inode *sin = vop_info(ip, sfs_inode);
acquire(&icache.lock);
if(sin->ref == 1 && (sin->flags & I_VALID) && sin->nlink == 0){
// inode has no links: truncate and free inode.
if(sin->flags & I_BUSY)
panic("iput busy");
sin->flags |= I_BUSY;
release(&icache.lock);
sfs_itrunc(ip);
sin->type = 0;
sfs_iupdate(ip);
acquire(&icache.lock);
sin->flags = 0;
wakeup(ip);
}
// cprintf("sin->inum = %d, sin->ref = %d\n", sin->inum, sin->ref);
sin->ref--;
// cprintf("sin->inum = %d, sin->ref = %d\n", sin->inum, sin->ref);
release(&icache.lock);
}
/*
* Delete a directory.
*
* Locking: Acquires vnode lock for parent dir and then vnode lock for
* victim dir. Releases both.
*
* Requires 4 buffers.
*/
static
int
sfs_rmdir(struct vnode *v, const char *name)
{
struct sfs_vnode *sv = v->vn_data;
struct sfs_fs *sfs = sv->sv_absvn.vn_fs->fs_data;
struct sfs_vnode *victim;
struct sfs_dinode *dir_inodeptr;
struct sfs_dinode *victim_inodeptr;
int result, result2;
int slot;
/* Cannot remove the . or .. entries from a directory! */
if (!strcmp(name, ".") || !strcmp(name, "..")) {
return EINVAL;
}
lock_acquire(sv->sv_lock);
reserve_buffers(SFS_BLOCKSIZE);
result = sfs_dinode_load(sv);
if (result) {
goto die_loadsv;
}
dir_inodeptr = sfs_dinode_map(sv);
if (dir_inodeptr->sfi_linkcount == 0) {
result = ENOENT;
goto die_linkcount;
}
result = sfs_lookonce(sv, name, &victim, &slot);
if (result) {
goto die_linkcount;
}
lock_acquire(victim->sv_lock);
result = sfs_dinode_load(victim);
if (result) {
goto die_loadvictim;
}
victim_inodeptr = sfs_dinode_map(victim);
if (victim->sv_ino == SFS_ROOTDIR_INO) {
result = EPERM;
goto die_total;
}
/* Only allowed on directories */
if (victim_inodeptr->sfi_type != SFS_TYPE_DIR) {
result = ENOTDIR;
goto die_total;
}
result = sfs_dir_checkempty(victim);
if (result) {
goto die_total;
}
result = sfs_dir_unlink(sv, slot);
if (result) {
goto die_total;
}
KASSERT(dir_inodeptr->sfi_linkcount > 1);
KASSERT(victim_inodeptr->sfi_linkcount==2);
dir_inodeptr->sfi_linkcount--;
sfs_dinode_mark_dirty(sv);
victim_inodeptr->sfi_linkcount -= 2;
sfs_dinode_mark_dirty(victim);
result = sfs_itrunc(victim, 0);
if (result) {
victim_inodeptr->sfi_linkcount += 2;
dir_inodeptr->sfi_linkcount++;
result2 = sfs_dir_link(sv, name, victim->sv_ino, NULL);
if (result2) {
/* XXX: would be better if this case didn't exist */
panic("sfs: %s: rmdir: %s; while recovering: %s\n",
sfs->sfs_sb.sb_volname,
strerror(result), strerror(result2));
}
goto die_total;
}
die_total:
sfs_dinode_unload(victim);
die_loadvictim:
lock_release(victim->sv_lock);
VOP_DECREF(&victim->sv_absvn);
die_linkcount:
sfs_dinode_unload(sv);
die_loadsv:
unreserve_buffers(SFS_BLOCKSIZE);
lock_release(sv->sv_lock);
return result;
}
/*
* Rename a file.
*
* Locking:
* Locks sfs_renamelock.
* Calls check_parent, which locks various directories one at a
* time.
* Locks the target vnodes and their parents in a complex fashion
* (described in detail below) which is carefully arranged so
* it won't deadlock with rmdir. Or at least I hope so.
* Then unlocks everything.
*
* The rationale for all this is complex. See the comments below.
*
* Requires up to 7 buffers.
*/
static
int
sfs_rename(struct vnode *absdir1, const char *name1,
struct vnode *absdir2, const char *name2)
{
struct sfs_fs *sfs = absdir1->vn_fs->fs_data;
struct sfs_vnode *dir1 = absdir1->vn_data;
struct sfs_vnode *dir2 = absdir2->vn_data;
struct sfs_vnode *obj1=NULL, *obj2=NULL;
struct sfs_dinode *dir1_inodeptr, *dir2_inodeptr;
struct sfs_dinode *obj1_inodeptr, *obj2_inodeptr;
int slot1=-1, slot2=-1;
int result, result2;
struct sfs_direntry sd;
int found_dir1;
/* make gcc happy */
obj2_inodeptr = NULL;
/* The VFS layer is supposed to enforce this */
KASSERT(absdir1->vn_fs == absdir2->vn_fs);
if (!strcmp(name1, ".") || !strcmp(name2, ".") ||
!strcmp(name1, "..") || !strcmp(name2, "..")) {
return EINVAL;
}
if (strlen(name2)+1 > sizeof(sd.sfd_name)) {
return ENAMETOOLONG;
}
/*
* We only allow one rename to occur at a time. This appears
* to be necessary to preserve the consistency of the
* filesystem: once you do the parent check (that n1 is not an
* ancestor of d2/n2) nothing may be allowed to happen that
* might invalidate that result until all of the
* rearrangements are complete. If other renames are allowed
* to proceed, we'd need to lock every descendent of n1 to
* make sure that some ancestor of d2/n2 doesn't get inserted
* at some point deep down. This is impractical, so we use one
* global lock.
*
* To prevent certain deadlocks while locking the vnodes we
* need, the rename lock goes outside all the vnode locks.
*/
reserve_buffers(SFS_BLOCKSIZE);
lock_acquire(sfs->sfs_renamelock);
/*
* Get the objects we're moving.
*
* Lock each directory temporarily. We'll check again later to
* make sure they haven't disappeared and to find slots.
*/
lock_acquire(dir1->sv_lock);
result = sfs_lookonce(dir1, name1, &obj1, NULL);
lock_release(dir1->sv_lock);
if (result) {
goto out0;
}
lock_acquire(dir2->sv_lock);
result = sfs_lookonce(dir2, name2, &obj2, NULL);
lock_release(dir2->sv_lock);
if (result && result != ENOENT) {
goto out0;
}
if (result==ENOENT) {
/*
* sfs_lookonce returns a null vnode with ENOENT in
* order to make our life easier.
*/
KASSERT(obj2==NULL);
}
/*
* Prohibit the case where obj1 is a directory and it's a direct
* ancestor in the tree of dir2 (or is the same as dir2). If
* that were to be permitted, it'd create a detached chunk of
* the directory tree, and we don't like that.
*
* If we see dir1 while checking up the tree, found_dir1 is
* set to true. We use this info to choose the correct ordering
* for locking dir1 and dir2.
*
* To prevent deadlocks, the parent check must be done without
* holding locks on any other directories.
*/
result = check_parent(dir1, obj1, dir2, &found_dir1);
if (result) {
goto out0;
}
/*
* Now check for cases where some of the four vnodes we have
* are the same.
*
* These cases are, in the order they are handled below:
*
* dir1 == obj1 Already checked.
* dir2 == obj2 Already checked.
* dir2 == obj1 Already checked.
* dir1 == obj2 Checked below.
* dir1 == dir2 Legal.
* obj1 == obj2 Legal, special handling.
*/
/*
* A directory should have no entries for itself other than '.'.
* Thus, since we explicitly reject '.' above, the names
* within the directories should not refer to the directories
* themselves.
*/
KASSERT(dir1 != obj1);
KASSERT(dir2 != obj2);
/*
* The parent check should have caught this case.
*/
KASSERT(dir2 != obj1);
/*
* Check for dir1 == obj2.
*
* This is not necessarily wrong if obj1 is the last entry in
* dir1 (this is essentially "mv ./foo/bar ./foo") but our
* implementation doesn't tolerate it. Because we need to
* unlink g2 before linking g1 in the new place, it will
* always fail complaining that g2 (sv1) isn't empty. We could
* just charge ahead and let this happen, but we'll get into
* trouble with our locks if we do, so detect this as a
* special case and return ENOTEMPTY.
*/
if (obj2==dir1) {
result = ENOTEMPTY;
goto out0;
}
/*
* Now we can begin acquiring locks for real.
*
* If we saw dir1 while doing the parent check, it means
* dir1 is higher in the tree than dir2. Thus, we should
* lock dir1 before dir2.
*
* If on the other hand we didn't see dir1, either dir2 is
* higher in the tree than dir1, in which case we should lock
* dir2 first, or dir1 and dir2 are on disjoint branches of
* the tree, in which case (because there's a single rename
* lock for the whole fs) it doesn't matter what order we lock
* in.
*
* If we lock dir1 first, we don't need to lock obj1 before
* dir2, since (due to the parent check) obj1 cannot be an
* ancestor of dir2.
*
* However, if we lock dir2 first, obj2 must be locked before
* dir1, in case obj2 is an ancestor of dir1. (In this case we
* will find that obj2 is not empty and cannot be removed, but
* we must lock it before we can check that.)
*
* Thus we lock in this order:
*
* dir1 (if found_dir1)
* dir2
* obj2 (if non-NULL)
* dir1 (if !found_dir1)
* obj1
*
* Also, look out for the case where both dirs are the same.
* (If this is true, found_dir1 will be set.)
*/
if (dir1==dir2) {
/* This locks "both" dirs */
lock_acquire(dir1->sv_lock);
KASSERT(found_dir1);
}
else {
if (found_dir1) {
lock_acquire(dir1->sv_lock);
}
lock_acquire(dir2->sv_lock);
}
/*
* Now lock obj2.
*
* Note that we must redo the lookup and get a new obj2, as it
* may have changed under us. Since we hold the rename lock
* for the whole fs, the fs structure cannot have changed, so
* we don't need to redo the parent check or any of the checks
* for vnode aliasing with dir1 or dir2 above. Note however
* that obj1 and obj2 may now be the same even if they weren't
* before.
*/
KASSERT(lock_do_i_hold(dir2->sv_lock));
if (obj2) {
VOP_DECREF(&obj2->sv_absvn);
obj2 = NULL;
}
result = sfs_lookonce(dir2, name2, &obj2, &slot2);
if (result==0) {
KASSERT(obj2 != NULL);
lock_acquire(obj2->sv_lock);
result = sfs_dinode_load(obj2);
if (result) {
/* ENOENT would confuse us below; but it can't be */
KASSERT(result != ENOENT);
lock_release(obj2->sv_lock);
VOP_DECREF(&obj2->sv_absvn);
/* continue to check below */
}
else {
obj2_inodeptr = sfs_dinode_map(obj2);
}
}
else if (result==ENOENT) {
/*
* sfs_lookonce returns a null vnode and an empty slot
* with ENOENT in order to make our life easier.
*/
KASSERT(obj2==NULL);
KASSERT(slot2>=0);
}
if (!found_dir1) {
lock_acquire(dir1->sv_lock);
}
/* Postpone this check to simplify the error cleanup. */
if (result != 0 && result != ENOENT) {
goto out1;
}
/*
* Now reload obj1.
*/
KASSERT(lock_do_i_hold(dir1->sv_lock));
VOP_DECREF(&obj1->sv_absvn);
obj1 = NULL;
result = sfs_lookonce(dir1, name1, &obj1, &slot1);
if (result) {
goto out1;
}
/*
* POSIX mandates that if obj1==obj2, we succeed and nothing
* happens. This is somewhat stupid if obj1==obj2 and dir1 != dir2,
* but we'll go with POSIX anyway.
*/
if (obj1==obj2) {
result = 0;
VOP_DECREF(&obj1->sv_absvn);
obj1 = NULL;
goto out1;
}
lock_acquire(obj1->sv_lock);
result = sfs_dinode_load(obj1);
if (result) {
lock_release(obj1->sv_lock);
VOP_DECREF(&obj1->sv_absvn);
obj1 = NULL;
goto out1;
}
obj1_inodeptr = sfs_dinode_map(obj1);
result = sfs_dinode_load(dir2);
if (result) {
goto out2;
}
dir2_inodeptr = sfs_dinode_map(dir2);
result = sfs_dinode_load(dir1);
if (result) {
goto out3;
}
dir1_inodeptr = sfs_dinode_map(dir1);
/*
* One final piece of paranoia: make sure dir2 hasn't been rmdir'd.
* (If dir1 was, the obj1 lookup above would have failed.)
*/
if (dir2_inodeptr->sfi_linkcount==0) {
result = ENOENT;
goto out4;
}
/*
* Now we have all the locks we need and we can proceed with
* the operation.
*/
/* At this point we should have valid slots in both dirs. */
KASSERT(slot1>=0);
KASSERT(slot2>=0);
if (obj2 != NULL) {
/*
* Target already exists.
* Must be the same type (file or directory) as the source,
* and if a directory, must be empty. Then unlink it.
*/
if (obj1_inodeptr->sfi_type == SFS_TYPE_DIR) {
if (obj2_inodeptr->sfi_type != SFS_TYPE_DIR) {
result = ENOTDIR;
goto out4;
}
result = sfs_dir_checkempty(obj2);
if (result) {
goto out4;
}
/* Remove the name */
result = sfs_dir_unlink(dir2, slot2);
if (result) {
goto out4;
}
/* Dispose of the directory */
KASSERT(dir2_inodeptr->sfi_linkcount > 1);
KASSERT(obj2_inodeptr->sfi_linkcount == 2);
dir2_inodeptr->sfi_linkcount--;
obj2_inodeptr->sfi_linkcount -= 2;
sfs_dinode_mark_dirty(dir2);
sfs_dinode_mark_dirty(obj2);
/* ignore errors on this */
sfs_itrunc(obj2, 0);
}
else {
KASSERT(obj1->sv_type == SFS_TYPE_FILE);
if (obj2->sv_type != SFS_TYPE_FILE) {
result = EISDIR;
goto out4;
}
/* Remove the name */
result = sfs_dir_unlink(dir2, slot2);
if (result) {
goto out4;
}
/* Dispose of the file */
KASSERT(obj2_inodeptr->sfi_linkcount > 0);
obj2_inodeptr->sfi_linkcount--;
sfs_dinode_mark_dirty(obj2);
}
sfs_dinode_unload(obj2);
lock_release(obj2->sv_lock);
VOP_DECREF(&obj2->sv_absvn);
obj2 = NULL;
}
/*
* At this point the target should be nonexistent and we have
* a slot in the target directory we can use. Create a link
* there. Do it by hand instead of using sfs_dir_link to avoid
* duplication of effort.
*/
KASSERT(obj2==NULL);
bzero(&sd, sizeof(sd));
sd.sfd_ino = obj1->sv_ino;
strcpy(sd.sfd_name, name2);
result = sfs_writedir(dir2, slot2, &sd);
if (result) {
goto out4;
}
obj1_inodeptr->sfi_linkcount++;
sfs_dinode_mark_dirty(obj1);
if (obj1->sv_type == SFS_TYPE_DIR && dir1 != dir2) {
/* Directory: reparent it */
result = sfs_readdir(obj1, DOTDOTSLOT, &sd);
if (result) {
goto recover1;
}
if (strcmp(sd.sfd_name, "..")) {
panic("sfs: %s: rename: moving dir: .. is not "
"in slot %d\n", sfs->sfs_sb.sb_volname,
DOTDOTSLOT);
}
if (sd.sfd_ino != dir1->sv_ino) {
panic("sfs: %s: rename: moving dir: .. is i%u "
"and not i%u\n", sfs->sfs_sb.sb_volname,
sd.sfd_ino, dir1->sv_ino);
}
sd.sfd_ino = dir2->sv_ino;
result = sfs_writedir(obj1, DOTDOTSLOT, &sd);
if (result) {
goto recover1;
}
dir1_inodeptr->sfi_linkcount--;
sfs_dinode_mark_dirty(dir1);
dir2_inodeptr->sfi_linkcount++;
sfs_dinode_mark_dirty(dir2);
}
result = sfs_dir_unlink(dir1, slot1);
if (result) {
goto recover2;
}
obj1_inodeptr->sfi_linkcount--;
sfs_dinode_mark_dirty(obj1);
KASSERT(result==0);
if (0) {
/* Only reached on error */
recover2:
if (obj1->sv_type == SFS_TYPE_DIR) {
sd.sfd_ino = dir1->sv_ino;
result2 = sfs_writedir(obj1, DOTDOTSLOT, &sd);
if (result2) {
recovermsg(sfs->sfs_sb.sb_volname,
result, result2);
}
dir1_inodeptr->sfi_linkcount++;
sfs_dinode_mark_dirty(dir1);
dir2_inodeptr->sfi_linkcount--;
sfs_dinode_mark_dirty(dir2);
}
recover1:
result2 = sfs_dir_unlink(dir2, slot2);
if (result2) {
recovermsg(sfs->sfs_sb.sb_volname,
result, result2);
}
obj1_inodeptr->sfi_linkcount--;
sfs_dinode_mark_dirty(obj1);
}
out4:
sfs_dinode_unload(dir1);
out3:
sfs_dinode_unload(dir2);
out2:
sfs_dinode_unload(obj1);
lock_release(obj1->sv_lock);
out1:
if (obj2) {
sfs_dinode_unload(obj2);
lock_release(obj2->sv_lock);
}
lock_release(dir1->sv_lock);
if (dir1 != dir2) {
lock_release(dir2->sv_lock);
}
out0:
if (obj2 != NULL) {
VOP_DECREF(&obj2->sv_absvn);
}
if (obj1 != NULL) {
VOP_DECREF(&obj1->sv_absvn);
}
unreserve_buffers(SFS_BLOCKSIZE);
lock_release(sfs->sfs_renamelock);
return result;
}
